|Rawles, Steven - Steve|
Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2003
Publication Date: 9/5/2003
Citation: RAWLES, S.D., LOCHMANN, R. EFFECTS OF AMYLOPECTIN/AMYLOSE STARCH RATIO ON GROWTH, BODY COMPOSITION AND GLYCEMIC RESPONSE OF SUNSHINE BASS MORONE CHRYSOPS E X M. SAXATILIS G. JOURNAL OF THE WORLD AQUACULTURE SOCIETY. 2003. v.34(3). p.278-288. Interpretive Summary: Starch is a natural compound made up of molecular "chains" of the sugar glucose. Starch complexity is determined by the amount of chain branching. In animal feeds, starch complexity can affect growth, liver size, and the accumulation of body fat. Large livers in fish sometimes indicate poor health or nutrition. A 10-week feeding trial was conducted at the HKD Stuttgart National Aquaculture Research Center to determine the effect of changing the ratio of highly-branched starch (amylopectin) to less complex starch (amylose) on the growth of hybrid striped bass fingerlings. Fish were fed semipurified diets containing 25% carbohydrate in which protein, energy, fat and carbohydrate levels were constant. Only the ratio of the type of starch in the diet was changed. Carbohydrate in the diets was either glucose, dextrin (acid-treated starch composed of unbranched glucose chains),or corn starch with different ratios of amylopectin and amylose. Weight gain was greater for fish fed diets which contained dextrin or the highest amount of amylose and lower in fish fed the other diets. Feed efficiency was higher in fish fed the diet containing the highest amount of amylose. Fish fed diets containing high-amylose cornstarch had the smallest livers. Body fat was lower in fish fed diets containing some amylose as compared to those fed diets without amylose. The chemical composition of fillets and the fillet yield were not affected by changing the type of starch in the diet. Blood sugar in fish fed diets with the highest amount of amylose starch was lower than in fish fed the other diets. These data suggest that feeding diets in which a greater portion of the starch is amylose may be a useful strategy for improving carbohydrate use in sunshine bass.
Technical Abstract: Manipulation of the ratio of amylopectin to amylose starches in the carbohydrate fraction of the diet has been used to improve carbohydrate and lipid metabolism in mammals. A 10-wk feeding trial was conducted to determine the effect of dietary amylopectin/amylose ratio on growth and composition of growth of advanced sunshine bass (Morone chrysops x M. saxatilis ) fingerlings. Fish were fed semipurified diets in which the level of protein, lipid, energy, and carbohydrate were held constant; only the type of carbohydrateor starch ratio was changed. Carbohydrate in the diets was composed of either glucose, dextrin, 100% amylopectin/0% amylose, 70% amylopectin/30% amylose, or 30% amylopectin/70% amylose. Weight gain ranged from 195 to 236 % of initial weight and was significantly greater (P < 0.1) for fish fed diets containing dextrin or the 70% amylose starch. Feed efficiency ranged from 0.52 to 0.61 and was higher in fish fed the diet containing the highest concentration of amylose. Hepatosomatic index was lowest (1.40 ¿ 1.45) in fish fed diets containing high-amylose cornstarch. Intraperitoneal fat ratio was lower in fish fed diets containing some amylose. Liver lipid was almost twice as high (7.3 ¿ 8.9 %) in fish fed the diets containing any starch. Glycogen in the liver decreased from 12 % in fish fed the diet containing glucose to 5 % in fish fed the diets containing amylose. Muscle composition and ratio were unaffected by the dietary treatments. The blood glucose profile of fish fed diets in which the starch was mostly amylose was lower that of fish fed the other diets. These data suggest that feeding diets in which a greater portion of the starch is amylose may be a useful strategy for improving carbohydrate use in sunshine bass.